Type. CANADA. BRITISH COLUMBIA. Vancouver Island, Botanical Beach, 4 km SW of Port Renfrew, on Picea sitchensis behind beach, 14 August 1975, W.J. Noble 5371 (UBC - holotype!, SASK - isotype!).
Description.Thallus thin, light to dark grey, areolate, areoles discrete, irregular, plane, to 0.30‑0.50 mm wide, usually becoming contiguous, ca. 1.20 mm wide; surface minutely rugose, matt; margin indeterminate; prothallus lacking; vegetative propagules absent. Apothecia quickly narrowly attached, frequent, becoming contiguous, to 0.90‑1.40 mm in diam.; disc black, rarely lightly pruinose, persistently plane or rarely becoming convex; thalline margin concolourous with thallus, ca. 0.10 mm wide, entire, sometimes becoming flexuose; excipular ring sometimes present, raised. Apothecial Anatomy. Thalline exciple 50‑110 µm wide laterally; cortex 10‑20 µm wide; epinecral layer absent; crystals present in cortex, absent from medulla; cortical cells to 4.0‑6.0 µm wide, not pigmented; algal cells to 10.0‑14.5 µm long; thalline exciple 100‑140 µm wide below, cortex expanded to (30‑)50‑70 µm, columnar, I+ blue; proper exciple typically pigmented light brown, 10‑20 µm wide laterally, to 30‑40 µm wide above; hypothecium colourless, 80‑120 µm deep, sometimes inspersed with oil; hymenium 100‑120 µm high, not inspersed; paraphyses 2.0‑2.5 µm wide, not conglutinate, rarely with a few oil paraphyses, apices to 4.0‑6.0 µm diam., lightly or darkly pigmented but immersed in dispersed pigment, forming a dark, red‑brown epihymenium; asci 80‑100 x 27‑30 µm. Ascospores 4-8/ascus, developmental type A, Physcia‑type, (25.0‑)30.0-32.5(‑37.5) x (12.5‑)14.5‑15.5(‑17.5) µm, retaining thick apical walls; torus narrow, becoming hidden by wall pigmentation; walls ornamented (often at x500), appearing ridged or not at high magnification (x1250). Pycnidia typically scarce, ca. 0.2 mm in diam., immersed, ostiole darkly pigmented; conidiophores highly gelatinized, Type I; conidia bacilliform, ca. 4.0 x 1.0 µm.
Chemistry. Spot tests, K+ yellow, C-, KC-, sometimes P+ faint yellow; secondary metabolites, atranorin in cortex, zeorin in medulla.
Substrate and Ecology.Rinodina macrospora inhabits driftwood, Abies, Cupressus macrocarpa and Picea sitchensis on coastal shorelines in the Pacific Northwest.
Distribution. A North American endemic now known from mid California to Haida Gwaii (Queen Charlotte Islands), British Columbia. Strictly maritime, this species belongs to the Oceanic element.
Notes. The very large areoles and apothecia of older thalli make R. macrospora a distinctive species. The large, Physcia-type spores, after which the species is named, and pigmented exciple might suggest a relationship with R. turfacea or R. badiexcipula. However, neither of these species have spores averaging >30 µm in length, possess walls with such well developed ornamentation, nor does either possess zeorin. Only R. oregana has spores of similar size but they belong to the Dirinaria-type, and have a very obvious Type B development. The secondary substances and spore type of R. macrospora may suggest a relationship with R. capensis, despite the much smaller spores of this species. One specimen (Brodo 9859, CANL, see Sheard & Mayrhofer 2002) possesses darkly pigmented cyanobacteria colonies immersed in the thallus surface that have the appearance of condiomata. Because of their integration within the thallus the colonies may function as cephalodia (see Poelt & Mayrhofer 1988).
The original description of R. macrospora does not mention that some asci may only develop four spores. In such material eight spores are differentiated but only four develop to maturity. Spores from four spored asci are larger than those with eight spores. Further examination also indicates that the hymenium is not inspersed. Some inspersion occurs in the hypothecium of some specimens and this is the origin of oil globules in the hymenium of squash preparations. However, a few oil paraphyses are sometimes scattered throughout the hymenium.
Specimens examined [not reported by Sheard and Mayrhofer (2002)]. CANADA. BRITISH COLUMBIA. Vancouver Island, Botanical Beach, W.J. Noble 5371 (SASK, UBC); Haida Gwaii (Queen Charlotte Islands), South Low Island, I.M. Brodo 17441 (CANL). U.S.A. CALIFORNIA. Monterey Co., Point Lobos State Reserve, P. van den Boom 29397 (personal herb.). OREGON. Tillamook Co., Cape Kiwanda State Park, B. McCune 22808; Cliff Creek Falls, B. McCune 26254 (both personal herb.).